Tricky issue needs resolution

[Polecatt]

I am experiencing an extremely challenging and frustrating issue that I'm hoping someone here might be able to help resolve. I have worked on this over months and replaced almost every piece of hardware in the process with no luck...

Here are the system specs.
Asus P5Q Motherboard
OCZ DDR2 PC2-6400 2GB (2x1024) platinum rev2 dual channel kit
Intel Core2 Duo Processor E8400 (6M Cache, 3.00 GHz, 1333 MHz FSB)
Sata dvd
sata HDD
SAPPHIRE HD 2600XT PCI-E video
OS windows XP (I have also tried with windows 7)

The issue shows up as corruption in large files that are processed by the system. This happens whether the file is introduced through the network, through a CD / DVD, or through USB.

I believe I have narrowed the probable cause down with a simple test. When I check the SHA hash value of a known good file on a USB key the hash value is incorrect and a different value is calculated each time.

The only 2 components which have not been replaced in this configuration are the CPU and the memory however testing of both these components shows no errors.

Any thoughts on what would cause this?? I suspect possible some type of hardware error that memtest or the cpu test dont check for or some other type of configuration issue.

 

[GhislainG]

Does Prime95 run without errors?

 

[Polecatt]

interesting... I just ran Prime95 and the PC died instantly and won't post anymore...

Any suggestions? The only thing I can get the mobo to respond to is if I remove the ram. Then I get a post message for no memory, otherwise I get fans and nothing else.

 

[GhislainG]

Prime95 doesn't cause systems to die. Are you sure that your PSU is working properly?

 

[Polecatt]

PSU is brand new although I have not verified it but seemed to be working fine since I installed it 2 weeks ago until I ran Prime 95. I also just tried a known good PSU and the system still won't post.

 

[GhislainG]

Although rare, it could be the CPU that went bad. Incorrect SHA hash value results could likely be caused by a bad CPU, particularly if the issue occurs when the file is read from a USB key or from the hard disk. Can you test the CPU in another system?

 

[Polecatt]

I'm going to see if I can get it tested tomorrow. I'll report back what I find.

Thanks.

 

[smorizio]

i had that issue on my p35 gigbyte board. found out the ram speed. i bouth some good corsair 1066 ram..the mb posted and ram memtest 100 precent fine but put it under load on install large files and it would damage files.swapped out to some slow 800 speed ram and the system been fine.I would check to see if your ram on the mb qal list.

 

[Polecatt]

After much hardware testing turns out it was the memory... For some reason initially, memtest was not finding errors. The only errors came up as large file decompression corruption and with the USB sha hash calculation and then prime 95 fried the ram completely. Again, this was all unexpected as memtest was showing no errors at all.

All other hardware have been tested good and the system posts and runs great with 2 new sticks of ram.

 

[Polecatt]

Best answer selected by Polecatt.

 

[nikorr]

This topic has been closed by Nikorr